Molded records, such as conventional audio records and the more recently developed high density information records, are manufactured by molding a thermoplastic composition between a pair of disc-shaped metal parts referred to as stampers. The stampers have formed in their molding surfaces a negative surface relief image corresponding to the information tracks desired to be formed in the molded record. A charge of a thermoplastic composition which is somewhat in excess of that actually required to form the record is used in order to insure that the molded record will be free of voids and low density areas. During the molding of the record, the excess amount of the thermoplastic composition is forced out from between the stampers and forms a ring of material about the outer edge of the record which is referred to as flash. The molded record with the flash still attached is removed from the surface of the stampers and thereafter, the flash is trimmed from the record. The trimmed record is then stored until it can be placed in a protective envelope, jacket or caddy.
When a relatively large number of records of a particular title are to be molded, it is customary to produce the records on an automated record press. A wide varity of different types of automated record presses have heretofore been suggested, many of which are now commercially available. These automated record presses, while varying considerably in their specific features, are generally characterized by having certain distinct work stations at which specific record manufacturing steps are performed. The work stations typically include, for example, a record pressing station, a record trimming station and generally, an on-machine temporary storage station. The record pressing stations have a press which include a pair of opposing molding platens which can be heated and cooled rapidly. The stampers having the information desired to be molded into the records are mounted on the molding platens. The record pressing station either includes as an integral part thereof or closely associated therewith, an extruder or the like for supplying a predetermined size charge of a thermoplastic composition to the record press in a timed relationship relative to operation of the stations of the record press. The charge of the thermoplastic composition is placed between the stampers mounted on the molding platens. The platens are heated to raise the thermoplastic composition above its melting point for molding and then are cooled to solidify the molten thermoplastic composition in the form of a record. The resulting molded record is then transferred to the record trimming station for removal of the flash. After the record is trimmed, it is then generally transferred to temporary on-machine storage station. Each of the steps in the record manufacturing process generally take place simultaneously with the other steps, that is, while a record is being molded, another record is being trimmed and so forth.
In the operation of an automated record press, it is highly important that there be a precisely timed and accurate transfer of the in-process parts such as the molded but untrimmed record between the work stations. The timing is important in that the faster parts can be transferred from station to station, the faster the automated record molding press can be cycled. The speed of transfer is not, however, as important as the accuracy with which the in-process parts are transferred from work station to work station. If a part such as a charge of the thermoplastic composition is not properly positioned in the record pressing station or a molded but untrimmed record not properly aligned on the record trimming station, it can cause a break in production which may require shutdown of the entire record molding press until the problem can be corrected. It is also important that in-process parts be relatively uniform from part to part so that the same processing condition can be used for all similar parts.
Considerable problems are, however, encountered in the molding of records using automated record presses. Many of these problems can be traced directly or indirectly to the apparatus used to transfer untrimmed molded records from the record pressing station to the record trimming station. As noted above, in the molding operation the excess material in the charge of the thermoplastic composition is pressed out from between the stampers and typically forms an irregular-shaped ring of flash about the outer diameter of the molded record. With transfer apparatus designed to hold the non-uniform flash during transfer, it is often difficult to obtain and maintain a satisfactory grip of the flash. Furthermore, because of the non-uniformity of the flash, the record is often held in an off-center position which in turn causes misalignment of the untrimmed record with the record trimming station. Even if a transfer mechanism is used which contacts the center of the record, the non-uniform flash still often interferes with proper feeding and alignment of the molded record. Attempts have been made to improve the grip of the transfer apparatus to the flash by contacting the flash while still in a molten condition. One such transfer apparatus has an over-sized transfer ring with eyelets which extends inwardly from the inside of the ring to engage the molten flash as it formed. This technique results in an improved grip for transfer purposes, but also results in it being extremely difficult to strip the record from the transfer ring once the record reaches the record trimming station. The resulting flash is also exceptionally irregular as a result of the intrusion of the eyelets into the flash.
Non-uniform flash, a problem normally caused by the molding process or by the transfer ring or a combination of both can cause considerable problems in trimming the flash from the record, such as breakouts, edge cracking and the like, when the cutter blade is brought into contact with the flash.
What would be highly advantageous would be a transfer apparatus for an automated record press which would result in a uniformly-shaped flash; would securely hold an untrimmed record during transfer from the record pressing station to the record trimming station; would accurately position the record on the record trimming station; and would then readily release the record.